Display device

ABSTRACT

A display device includes plural unit areas each of which includes low definition pixels as sub-pixels larger than a specified standard and high definition pixels as sub-pixels smaller than the specified standard and which are regularly arranged. The low definition pixels include a blue pixel and a red pixel, and the high definition pixels include a white pixel and a green pixel.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese applicationJP2014-225297 filed on Nov. 5, 2014, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device.

2. Description of the Related Art

In a display device, in general, three-color sub-pixels of a red (R)pixel, a green (G) pixel and a blue (B) pixel having the same area arearranged side by side in a unit area corresponding to a main pixel, andthese three kinds of sub-pixels are arranged in a stripe form in adisplay area where plural unit areas are regularly arranged.

Besides, there is also known an arrangement which is different from thegeneral arrangement as stated above and in which one main pixel includestwo colors of GR or GB and two kinds of sub-pixels are alternatelyspread. In each main pixel in this arrangement, for example, the area ofa green pixel is ½ of the area of a blue pixel or a red pixel, and thenumber of sub-pixels decreases as compared with the general arrangement.However, almost comparable color reproducibility can be realized.

JP 2014-056819 A discloses a pixel arrangement structure of an organiclight-emitting display device in which a pixel aperture ratio isimproved and a gap between pixels is efficiently set.

Here, in order to reduce power consumption of a display device, it isconceivable to provide a white (W) pixel in a unit area in addition toRGB pixels.

However, there is a problem how to provide the white sub-pixel in a casewhere one unit area includes a green sub-pixel (high definition pixel)having a small area to improve definition and a red and a blue sub-pixel(low definition pixel) having a large area to reduce pixel integrationdegree in a display area.

SUMMARY OF THE INVENTION

The invention has an object to realize power consumption reduction byadopting a white pixel in at least one sub-pixel in a display device inwhich a unit area including a high definition pixel and a low definitionpixel is arranged.

In view of the above, according to the invention, a display deviceincludes plural unit areas each of which includes low definition pixelsas sub-pixels larger than a specified standard and high definitionpixels as sub-pixels smaller than the specified standard and which areregularly arranged. The low definition pixels include a blue pixel (B)and a red pixel (R), and the high definition pixels include a whitepixel (W) and a green pixel (G).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view schematically showing a display device of a firstembodiment.

FIG. 2 is a sectional view of a pixel of the display device of the firstembodiment.

FIG. 3 is a view showing a pixel arrangement of the display device ofthe first embodiment.

FIG. 4 is a view showing a pixel arrangement of a display device ofmodified example 1 and modified example 2 of the first embodiment.

FIG. 5 is a view showing a pixel arrangement of a display device ofmodified example 3 of the first embodiment.

FIG. 6 is a view showing a pixel arrangement of a display device of asecond embodiment.

FIG. 7 is a view showing a pixel arrangement of a display device ofmodified example 1 of the second embodiment.

FIG. 8 is a view showing a pixel arrangement of a display device ofmodified example 2 of the second embodiment.

FIG. 9 is a view showing a pixel arrangement of a display device ofmodified example 3 of the second embodiment.

FIG. 10 is a view showing a pixel arrangement of a display device ofmodified example 4 of the second embodiment.

FIG. 11 is a view showing a pixel arrangement of a display device of athird embodiment.

FIG. 12 is a view showing a pixel arrangement of a display device of afourth embodiment and a pixel arrangement of a display device ofmodified example 1 of the fourth embodiment.

FIG. 13 is a view showing a pixel arrangement of a display device of afifth embodiment and a pixel arrangement of a display device of modifiedexample 1 of the fifth embodiment.

FIG. 14 is a view showing a section of a transparent pixel of thedisplay device of the modified example 1 of the fifth embodiment.

FIG. 15 shows an example of a sectional schematic view of a pixel areain the display device of a separately coloring system of the modifiedexample 1 of the fifth embodiment.

FIG. 16 is a view for explaining a relation between a unit area M and animage address in the respective embodiments.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, display devices according to respective embodiments of theinvention will be described with reference to the drawings.

First Embodiment

A display device of a first embodiment is an organic EL display devicein which plural organic electroluminescence elements are arranged in adisplay area. FIG. 1 is a schematic plan view of an organic EL displaydevice 1 of the embodiment. The organic EL display device 1 isconstructed such that an opposite substrate B2 is bonded to an elementsubstrate B1 on which plural organic electroluminescence elements arearranged. A driver IC for driving the organic EL display device 1 isdisposed in an area of the element substrate B1 where the oppositesubstrate B2 is exposed.

Plural pixels emitting lights of red, green, blue and white areregularly arranged as described later in a display area DP of theorganic EL display device 1, and each of the pixels includes an organicelectroluminescence element (self light-emitting element). As shown inFIG. 1, a first scanning line BG, a second scanning line SG, a resetwiring Vrst and a video signal line Data are connected to the respectivepixels of the display area DP. The first scanning line BG, the secondscanning line SG and the reset wiring Vrst are respectively provided inparallel to an X-direction, and the video signal line Data is providedin parallel to a Y-direction. Besides, although omitted in FIG. 1,plural power supply lines to supply power to the respective selflight-emitting elements are provided in parallel to the Y-direction.Incidentally, the X-direction is a horizontal direction in which a shortside of the element substrate B1 extends in FIG. 1, and the Y-directionis a vertical direction in which a long side of the element substrate 1extends in FIG. 1.

FIG. 2 is a sectional schematic view of a pixel area in the organic ELdisplay device 1 of the first embodiment. In the organic EL displaydevice 1 of the first embodiment, an organic layer OL emitting whitelight is formed in common to the respective pixels over the wholesurface of the display area DP, and the light emitted from the organiclayer OL is colored in the opposite substrate B2 (color filtersubstrate) including an RGB color filter layer CF. Accordingly, theorganic EL display device 1 of the embodiment is a self light-emittingdisplay device of top emission type.

Besides, the organic layer OL is sandwiched between a lower electrode PXformed in each pixel and an upper electrode CD formed over the wholesurface of the display area DP, and light is emitted by recombination ofholes and electrons respectively injected from the lower electrode PXand the upper electrode CD.

Further, as shown in the drawing, the lower electrode PX of each pixelis formed on a flattening film PL formed of an organic insulating filmto eliminate a step generated by a switching element, and the respectivelower electrodes PX are separated by a bank layer BK for separatingpixels. A black matrix BM formed on the opposite substrate B2 roughlycorresponds to the bank layer BK, and partitions the respective colorfilter layers CF on the opposite substrate B2. A protecting layer PR forprotecting the organic layer OL is formed above the upper electrode CD,and a filling material PU is inserted between the opposite substrate B2and the element substrate B1. A transistor TR is arranged under theflattening film PL and on the substrate B1. Although not particularlyrestricted, the transistor TR includes a semiconductor region formed ofpolysilicon or the like, a gate insulating film formed on thesemiconductor region, a gate electrode formed on the gate insulatingfilm, a source electrode connected to the semiconductor region andformed of a conductive material such as metal in a contact hole of thegate insulating film, and a drain electrode connected to thesemiconductor region and formed of a conductive material such as metalin a contact hole of the gate insulating film. A contact hole is formedin the flattening film PL above the drain electrode and the insulatingfilm thereunder, and a contact CH is formed in the contact hole. Thecontact CH is connected to the lower electrode PX.

Here, FIG. 3 is a view showing a pixel layout of the display area DP inthe organic EL display device 1 of the embodiment.

As shown on the left side of FIG. 3, a low definition pixel as asub-pixel larger than a specified standard and a high definition pixelas a sub-pixel smaller than the specified standard are arranged in thedisplay area DP of the embodiment. The low definition pixel is forreducing manufacturing load by decreasing the integration degree ofpixels constituted of switching elements and the like. The highdefinition pixel is for improving the definition by compensating pixelroughness due to the low definition pixel. The low definition pixel andthe high definition pixel are laid out in the display area DP, so that,as compared with a case of a general strip pixel arrangement, the numberof sub-pixels is decreased, and comparable color reproducibility andsmoothness of a video can be realized.

Besides, the specified standard for classifying the high definitionpixel and the low definition pixel in the embodiment is an open area ofthe black matrix BM. The R pixel and the B pixel as the low definitionpixel have a larger open area than the G pixel and the W pixel as thehigh definition pixel. The W pixel of the embodiment is colorfilterless, a portion between the black matrices is blank, and the Wpixel emits light at a higher luminance than pixels of other colors.That is, in the display device of the embodiment, a signal processingsystem for coping with the introduction of the W pixel is adopted, ahighly efficient light emission luminance adjustment function isrealized, and the high luminance light emitting W pixel is in charge ofthe common white component formed by RGB pixels. Thus, the lightemission of the RGB pixels can be reduced, and the power consumption canbe reduced. As stated above, the W pixel is for suppressing the powerconsumption of the display device by securing the luminance. Thus, the Wpixel is preferably made to belong to the high definition pixel, insteadof making the W pixel belong to the low definition pixel larger than thespecified standard. Besides, when the W pixel is made to belong to thehigh definition pixel, not the low definition pixel, a high saturationimage becomes easy to be displayed.

Besides, as shown on the left side of FIG. 3, the low definition pixelsare arranged in a matrix form at a first pitch in the horizontaldirection and a second pitch in the vertical direction. The highdefinition pixels are arranged in a matrix form at the same pitch asthat of the low definition pixel, and are shifted with respect to thelow definition pixels by a distance smaller than the first pitch in thehorizontal direction and by a distance smaller than the second pitch inthe vertical direction. Specifically, as shown on the right side of FIG.3, the pixel centers of the low definition pixels are arranged tooverlap a first lattice point group including plural lattice points F(black dots) arranged in a rectangular lattice shape (specifically,square lattice shape). The pixel centers of the high definition pixelsare arranged to overlap a second lattice point group including plurallattice points S (white dots) arranged in a rectangular lattice shape atpositions shifted from the first lattice point group by a half pitch inthe vertical direction and in the horizontal direction.

Besides, as shown on the left side of FIG. 3, the R pixel and the Bpixel as the low definition pixel are alternately arranged in thevertical direction and in the horizontal direction. In the lowdefinition pixels in the embodiment, an inter-pixel distance in thevertical direction or the horizontal direction is smaller than that inan oblique direction of 45 degrees, and the R pixel and the B pixel arealternately arranged in the vertical direction and the horizontaldirection in which the inter-pixel distance of the low definition pixelsbecomes small. In other words, the R pixel and the B pixel arealternately arranged in the direction corresponding to the minimuminter-lattice point distance in the first lattice point group. Thisprevents the R pixels and the B pixel having large pixel areas fromapproaching each other and prevents light emission of the same colorfrom becoming locally noticeable.

The high definition pixel is arranged to fill a space between two lowdefinition pixels adjacent to each other in the oblique direction of 45degrees in which the inter-lattice point distance of the low definitionpixels is large. In the embodiment, as shown on the left side of FIG. 3,the high definition pixels are arranged so that the ratio of the numberof the G pixels to the number of the W pixels is 3 to 1. The G pixelshave higher contribution to definition recognition than the W pixels.The number of the G pixels is made larger than that of the W pixels, sothat the definition can be improved. Besides, a unit area correspondingto a main pixel on the left side of FIG. 3 is defined as indicated by abroken line frame M, and the unit areas each constituted of thesub-pixels of the same arrangement are arranged in the vertical andhorizontal directions. In each of the unit areas, the R pixels and the Bpixels are more thinned than the G pixels, and the number of the Gpixels is larger than the number of the R pixels and the number of the Bpixels.

Besides, with respect to the opening area of the sub-pixel, that of theG pixel and the W pixel as the high definition pixel is smaller thanthat of the R pixel and the B pixel as the low definition pixel, andfurther, that of the W pixel is preferably smaller than that of the Gpixel. In FIG. 3, each sub-pixel has a diamond shape in which a squareis inclined by 45 degrees and is arranged. However, the invention is notlimited to the form, and the opening portion of the pixel may haveanother shape. Incidentally, in FIG. 3, the W pixel has no hatching, theG pixel is indicated by hatching extending to the lower right, the Bpixel is indicated by horizontal hatching, and the R pixel is indicatedby vertical hatching.

Next, the left side of FIG. 4 is a view showing a pixel layout of thedisplay area DP in modified example 1 of the first embodiment, and theright side of FIG. 4 is a view showing a pixel layout of the displayarea DP in modified example 2 of the first embodiment. In the modifiedexample 1, the ratio of the number of G pixels to the number of W pixelsis 7:1, and a unit area M1 as a main pixel including the W pixel and aunit area M2 as a main pixel not including the W pixel are alternatelyarranged. In other words, part of the plural G pixels existing in theunit area M2 is replaced by the W pixel in the unit area M1, and hereby,the picture quality is improved as compared with the example of FIG. 3.

In the modified example 2, the ratio of the number of G pixels to thenumber of W pixels is 3:1, and the arrangement positions of the W pixelsin a unit area M1 and a unit area M2 adjacent to each other aredifferent from each other. Hereby, the picture quality is improved ascompared with the left side of FIG. 4. Besides, in another viewpoint,high definition pixel columns in which the W pixels are arranged existat an interval of one column, and the arrangements of the W pixels areshifted in the vertical direction in two high definition pixel columnsincluding the W pixels and adjacent to each other.

FIG. 5 is a view showing a pixel layout of the display area DP inmodified example 3 of the first embodiment. As shown in the drawing, inthe modified example 3, high definition pixels include a cyan (Cy)pixel, a magenta pixel (Mg) pixel and a yellow pixel in addition to a Gpixel and a W pixel. High definition pixel columns in which the Cypixels, the Mg pixels and the Y pixels are arranged exist at an intervalof one column. In one column, one of the Cy pixel, the Mg pixel and theY pixel and the G pixel are alternately arranged. A high definitionpixel column in which the G pixel and the W pixel are alternatelyarranged exists between high definition pixel columns in which the Cypixels, the Mg pixels and the Y pixels are respectively arranged.Besides, the Cy, Mg and Y pixels and the W pixel are arranged indifferent rows and are prevented from being adjacent to each other, sothat the picture quality is improved. (In other words, in the verticaland horizontal directions in the second lattice point groupcorresponding to the high definition pixel arrangement, the G pixel andW pixel are adjacent to each other, the G pixel and the Cy, Mg and Ypixels are adjacent to each other, and the W pixel is not adjacent tothe Cy, Mg and Y pixels at the minimum inter-lattice point distance inthe second lattice point group.) Incidentally, in FIG. 5, the Y pixel isindicated by oblique hatching extending to the lower left. The Cy pixelis indicated by horizontal hatching and the hatching interval thereof islarger than that of the B pixel. The Mg pixel is indicated by verticalhatching and the hatching interval thereof is larger than that of the Rpixel.

Second Embodiment

Next, a second embodiment of the invention will be described. FIG. 6 isa view showing a pixel layout of a display area DP in an organic ELdisplay device 1 of the second embodiment.

As shown on the left side of FIG. 6, in the pixel layout of the secondembodiment, although the density of low definition pixels is lower thanthat of the case of the first embodiment, the number of high definitionpixels is increased, and a smoother image display is realized.

In the second embodiment, as shown on the right side of FIG. 6, pixelcenters of low definition pixels corresponding to R pixels and B pixelsare arranged so as to overlap a first lattice point group includingplural lattice points F (black dots) arranged in an oblique latticeshape, and high definition pixels are arranged around the low definitionpixel. As shown also on the left side of FIG. 6, the high definitionpixels are arranged in the vertical direction, in the horizontaldirection and in the oblique direction of 45 degrees with respect to thelow definition pixel. In the pixel arrangement of the second embodiment,eight high definition pixels are arranged around one low definitionpixel.

The R pixels and the B pixels included in the low definition pixels arealternately arranged at plural lattice points lined up at a minimuminter-lattice point distance in the first lattice point group (that is,since the first lattice point group has an oblique lattice-shapedarrangement, the pixels are alternately arranged in the obliquedirection of 45 degrees). This prevents light-emission colors of the lowdefinition pixels from collectively recognized. Besides, as shown on theleft side of FIG. 6, G pixels (including G1 pixels and G2 pixelsdescribed later) are more arranged than W pixels, and the ratio of the Gpixels to the W pixels is 3:1. The G pixel is arranged between the Rpixel and the B pixel alternately arranged in the oblique direction. TheW pixel is arranged at the center position of four lattice pointsconstituting one unit of the oblique lattice in the first lattice pointgroup.

The pixel centers of the high definition pixels are arranged to overlapa second lattice point group constituted of plural lattice points S(white dots) arranged in an oblique lattice shape shifted by a halfpitch in the vertical direction or the horizontal direction with respectto the first lattice point group, and a third lattice point groupconstituted of plural lattice points T (rhombus) arranged in arectangular lattice shape in which a pitch in the vertical direction andthe horizontal direction is almost half that of the first lattice pointgroup (see the right side of FIG. 6). Incidentally, the pixel centers ofthe high definition pixels may not be necessarily arranged in the secondlattice point group and the third lattice point group. For example, thepixel centers of the high definition pixels may be arranged on a latticepoint group shifted by ⅓ pitch in the vertical and horizontal directionswith respect to the first lattice point group, and the arrangement ofthe high definition pixels is not limited to the arrangement of theembodiment.

Besides, in the second embodiment, the inter-pixel distance between theW pixel and the R or B pixel is larger than the inter-pixel distancebetween the G pixel and the R or B pixel. The influence of the W pixelon the R pixel or the B pixel with low visibility is reduced, and thepicture quality is improved.

With respect to the opening area of the sub-pixel, that of the G pixeland the W pixel as the high definition pixel is smaller than that of theR pixel and the B pixel as the low definition pixel, and further, thatof the W pixel is preferably smaller than that of the G pixel. In FIG.3, although each sub-pixel has a diamond shape in which the square isinclined in the direction of 45 degrees and is arranged, the inventionis not limited to the form, and the opening portion of the pixel mayhave another shape.

Especially, in the organic EL display device 1 of the second embodiment,the G pixels correspond to two kinds of pixels, that is, the G1 pixeland the G2 pixel. A color filter layer CF for obtaining dense greenlight is formed for the former pixel, and a color filter layer forobtaining pale green light is formed for the latter pixel. Since the twokinds of G pixels are included in the unit area, a smooth display isobtained.

Incidentally, in the G1 pixel and the G2 pixel, it is also acceptablethat the color filter layers CF for obtaining the same green are formed,the G1 pixel is made to emit dark green light by signal processing, andthe G2 pixel is made to emit bright green light by signal processing.For example, it is also acceptable that the G1 pixel emits light with aluminance value in a first range, the G2 pixel emits light with aluminance value in a second range, and the center value of the firstrange is lower than the center value of the second range. The G1 pixeland the G2 pixel are alternately arranged, so that a smooth display isobtained. Incidentally in FIG. 6, the G1 pixel is indicated by obliquehatching extending to the lower right, and the G2 pixel is indicated byoblique hatching extending to the lower right and the hatching intervalthereof is wider than that of the G1 pixel.

FIG. 7 is a view showing a pixel arrangement of an organic EL displaydevice 1 of modified example 1 of the second embodiment. As shown in thedrawing, in the display area DP of the modified example 1, G pixelscorresponds to two kinds of pixels, that is, a G1 pixel and a G2 pixel.A color filter layer CF for obtaining dark green light is formed for theformer pixel, and a color filter layer CF for obtaining pale green lightis formed for the latter pixel. The modified example 1 is different fromthe case of FIG. 6 in that the G1 pixels and the G2 pixels form a linein an oblique direction of 45 degrees and are continuously arranged(continuously arranged at half of a pitch of the low definition pixelsin the oblique direction). Since the G1 pixel and the G2 pixel are closeto each other and are arranged without another color pixel sandwichedtherebetween, a color filter substrate can be easily formed.

FIG. 8 is a view showing a pixel arrangement of an organic EL displaydevice 1 of modified example 2 of the second embodiment. As shown on theleft side of FIG. 8, the modified example is different from the case ofFIG. 7 in that a G pixel of a display area DP of the modified example 2is formed as an extending pixel which extends in a specified directionand has a size larger than a low definition pixel.

The extending pixel of the modified example has such a shape that thetwo pixels (G pixel and G2 pixel) of FIG. 7 are connected, and room canbe provided for the arrangement of a pixel circuit as compared with thecase of FIG. 6 or FIG. 7.

Here, the extending pixel will be described in more detail by using theright side of FIG. 8. A first lattice point F1, a second lattice pointF2, a third lattice point F3 and a fourth lattice point F4 shown on theright side of FIG. 8 indicate four lattice points arranged in thecircumferential direction of the square as the minimum lattice unit inthe first lattice point group arranged in the oblique lattice shape. Afirst low definition pixel L1 is arranged at the first lattice point F1,a second low definition pixel L2 is arranged at the second lattice pointF2, a third low definition pixel L3 is arranged at the third latticepoint F3, and a fourth low definition pixel L4 is arranged at the fourthlattice point F4. A first high definition area H1 is arranged betweenthe first low definition pixel L1 and the second low definition pixelL2, a second high definition area H2 is arranged between the second lowdefinition pixel L2 and the third low definition pixel L3, a third highdefinition area H3 is arranged between the third low definition pixel L3and the fourth low definition pixel L4, and a fourth high definitionarea H4 is arranged between the fourth low definition pixel L4 and thefirst low definition pixel L1.

Besides, a fifth high definition area H5 is arranged at an intersectionpoint (center position of the square as the minimum lattice unit)between a straight line connecting the first lattice point F1 and thethird lattice point F3 and a straight line connecting the second latticepoint F2 and the fourth lattice point F4. Each extending pixel EX isformed to straddle the fifth high definition area H5 and one of thefirst to the fourth high definition areas H1 to H4.

In another viewpoint, the extending pixel EX of the modified exampleextends to include the middle point on one side of the squareconstituting the minimum lattice unit in the first lattice point groupand the intersection point between the diagonal lines of the square, andextends so as to overlap one lattice point S belonging to the secondlattice point group and one lattice point T adjacent to the latticepoint S and belonging to the third lattice point group.

Incidentally, the shape of the extending pixel EX may not be necessarilythe rectangular shape, and may have an elliptical shape or anothershape. However, at least the opening area thereof is made smaller thanthat of the low definition pixel.

FIG. 9 is a view showing a pixel arrangement of an organic EL displaydevice 1 in modified example 3 of the second embodiment. As shown in thedrawing, the organic EL display device 1 of the modified example 3 isdifferent from that of the case of FIG. 7 in the arrangement of W pixelsand G pixels and in that the opening area of the W pixel is smaller thanthat of the G pixel.

Specifically, the pixel centers of the W pixels are arranged tocorrespond to the rectangular lattice-shaped third lattice point groupto which the plural lattice points T belong, and the pixel centers ofthe G pixels are arranged to correspond to the oblique lattice-shapedsecond lattice point group to which the plural lattice points S belong.Besides, although the number of the W pixels is larger than the numberof the G pixels in a unit area M corresponding to a main pixel, theopening area of the W pixel is made smaller than that of the G pixel tokeep balance, so that the G pixel having high contribution to definitionrecognition is made noticeable.

As stated above, the number of the W pixels each having the opening areasmaller than that of the G pixel is made larger than the number of the Gpixels, so that a space for forming a contact CH and the like is easilysecured, and manufacturing load can be reduced. Besides, the four Wpixels in the unit area M may be controlled to have the same luminance.In this case, a signal may be branched and supplied to the four W pixelsfrom the same video signal line Data, or a signal may be supplied fromone video signal line Data to a pixel electrode PX formed to extend overfour W pixels in the unit area M. Besides, a pixel electrode PX isformed to include at least two lattice points T belonging to the thirdlattice point group, and a signal may be supplied from one video signalline Data to the pixel electrode PX including the two lattice points T.Incidentally, the contact CH is arranged between the opening of the Wpixel and the opening of the G pixel with respect to the W pixel, isarranged between the opening of the W pixel and the opening of the Gpixel with respect to the G pixel, is arranged between the opening ofthe W pixel and the opening of the B pixel with respect to the B pixel,and is arranged between the opening of the W pixel and the opening ofthe R pixel with respect to the R pixel. With respect to the G pixel,the B pixel and the R pixel, the contact CH is provided between one ofthem and the W pixel having the smallest opening. With respect to the Wpixel, since the W pixel having the smallest opening does not existadjacently, the contact CH is provided between the W pixel and the Gpixel. By doing so, while the respective pixels are made adjacent toeach other, the contact CH can be provided.

FIG. 10 is a view showing a pixel arrangement of an organic EL displaydevice 1 of modified example 4 of the second embodiment. As shown in thedrawing, in the modified example 4, high definition pixels include acyan (Cy) pixel, a magenta (Mg) pixel and a yellow (Y) pixel in additionto a G pixel and a W pixel. Specifically, the Cy, Mg and W pixels arearranged at the lattice points T corresponding to the third latticepoint group, and the G pixel is arranged at the lattice point Scorresponding to the second lattice point group. As stated above, sincethe Cy, Mg and Y pixels are included in the high definition pixels, theorganic EL display device 1 of higher image quality can be realized.Besides, the opening areas of the high definition pixels may be changedbased on colored colors.

Although the organic EL display device 1 of the second embodiment andthe modified examples thereof are described in the above, thedescription is made mainly on the different points from the organic ELdisplay device 1 of the first embodiment, and the description of almostthe same point as that of the case of the first embodiment is suitablyomitted.

Third Embodiment

Next, a third embodiment of the invention will be described. FIG. 11 isa view showing a pixel layout of a display area DP in an organic ELdisplay device 1 of the third embodiment.

As shown on the left side of FIG. 11, in the organic EL display device 1of the third embodiment, a pair of R pixel and B pixel are arranged tobe adjacent to each other so that a high definition pixel does not existtherebetween, and high definition pixels each having a size larger in aspecified direction than a low definition pixel are arranged aroundthem. Since the pair of low definition pixels are arranged to be closeto each other, many extending pixels are easily arranged as comparedwith the case of the modified example 2 (FIG. 8) of the secondembodiment, and more room can be provided for the arrangement of a pixelcircuit.

Here, the extending pixel will be described in more detail by using theright side of FIG. 11. In the display area DP of the embodiment, first,pixel centers of the B pixels are arranged to overlap a first latticepoint group in which plural lattice points F are arranged in arectangular lattice shape. The R pixels are arranged to be adjacent tothe respective B pixels in an oblique direction of 45 degrees (diagonaldirection of the square constituting the minimum lattice unit in thefirst lattice point group). The R pixel is arranged based on a latticepoint S (white dot) shifted by ¼ pitch in the vertical direction and ¼pitch in the horizontal direction with respect to the lattice point F(black dot) belonging to the first lattice point group.

The high definition pixels arranged to fill the surroundings of the pairof B pixel and R pixel are the extending pixels each having the sizelonger than that of the low definition pixel in the diagonal directionof the square constituting the minimum lattice unit in the first latticepoint group. In other words, the extending pixel in the embodimentextends in the diagonal direction of the square of the minimum latticeunit in the first lattice point group from one of a point (X) shifted by½ pitch in the vertical direction from the lattice point F, a point (X)shifted by ½ pitch in the horizontal direction and a point (X) shiftedby ½ pitch in the vertical direction and in the horizontal direction,and reaches a point (triangle) shifted by ¼ pitch in the verticaldirection and in the horizontal direction with respect to the one ofthese points.

Incidentally, the shape of the extending pixel may not be necessarily arectangular shape, and may have an elliptical shape or another shape.However, at least the opening area thereof is made smaller than that ofthe low definition pixel.

Although the organic EL display device 1 of the third embodiment isdescribed in the above, the description is made mainly on the differentpoints from the organic EL display device 1 of the second embodiment,and the description of almost the same point as that of the case of thesecond embodiment is suitably omitted.

Fourth Embodiment

Next, a fourth embodiment of the invention will be described. FIG. 12 isa view showing a pixel layout of a display area DP in an organic ELdisplay device 1 of the fourth embodiment.

As shown on the left side of FIG. 12, in the organic EL display device 1of the fourth embodiment, low definition pixels include a W pixel, Rpixels and B pixels are more thinned than G pixels, and part of the Bpixels are replaced by the W pixels. In the low definition pixels ofeach unit area M, the ratio of the R pixel, the B pixel and the W pixelis 4:3:1. Besides, the positions of the W pixels are arranged to becomethe same in the unit areas M adjacent to each other in the horizontaldirection, and the positions of the W pixels are arranged to becomealternate in the unit areas M adjacent to each other in the verticaldirection.

Since part of the B pixels as the low definition pixels are replaced bythe W pixels, the white color is assigned to the blue color having lowvisibility, and a bad influence on the resolution can be reduced.

The right side of FIG. 12 is a view showing a pixel layout of a displayarea DP of an organic EL display device 1 of modified example 1 of thefourth embodiment. As shown on the right side of FIG. 12, the displayarea DP of the modified example 1 is different from the case of the leftside of FIG. 12 in that part of B pixels of the low definition pixelsare replaced by W pixels, and further, the W pixels are included also inthe high definition pixels. Incidentally, on the left side and the rightside of FIG. 12, although each sub-pixel has a diamond shape in which asquare is inclined in a direction of 45 degrees and is arranged, theinvention is not limited to the form, and the opening portion of thepixel may have another shape.

Although the organic EL display device 1 of the fourth embodiment isdescribed in the above, the description is made mainly on the differentpoints from the organic EL display device 1 of the first embodiment, andthe description of almost the same point as that of the case of thefirst embodiment is suitably omitted.

Fifth Embodiment

A fifth embodiment of the invention will be described. FIG. 13 is a viewshowing a pixel layout of a display area DP in an organic EL displaydevice 1 of the fifth embodiment.

As shown on the left side of FIG. 13, the organic EL display device 1 ofthe fifth embodiment includes a transparent pixel TP, in addition to alow definition pixel and a high definition pixel in a unit area M, andis a transparent display. Besides, the arrangement of the low definitionpixels on the left side of FIG. 13 is the same as that of the lowdefinition pixels of FIG. 6 according to the second embodiment, and thetransparent pixel (transparent opening) TP, and the G pixel and the Wpixel as the high definition pixels are arranged around the lowdefinition pixel.

The right side of FIG. 13 is a view showing a pixel layout of a displayarea DP of modified example 1 of the organic EL display device 1 of thefifth embodiment. As shown in the drawing, in the modified example 1,the transparent pixel TP is further arranged instead of the W pixel, andthe transparency of the display is further improved.

Besides, since the W pixel is not arranged in the modified example 1,coloring is performed more preferably by separately painting the organiclayer OL in RGB than by arranging the color filter layer CF on theopposite substrate B2.

FIG. 14 is a view showing an example of a section of the transparentpixel TP of the modified example 1 in which coloring is performed byseparately painting the organic layer OL. The organic layer OL, a lowerelectrode PX and the like do not exist in the transparent pixel TP, andlight passes through to the outside of an opposite substrate B2 from anelement substrate B1 side, and the transparent display is realized bythis.

Incidentally, in the case of the modified example 1 in which coloring isperformed by separately painting the organic layer OL, as shown in FIG.14, a black matrix BM may not be formed on the opposite substrate B2. Alight-emitting layer of the organic layer OL is shaped to be separatelypainted for each pixel. Besides, part of the organic layer OL(specifically, an electron injection layer, an electron transport layer,a hole transport layer and a hole injection layer) may be formed to becommon to the transparent pixel TP and the other pixels. Besides,although the bank layer BK and the organic layer OL are not formed inFIG. 14, these may exist also in the transparent pixel TP, and may beformed so that the organic layer OL is divided by the bank layer BK ineach pixel. Besides, in the transparent pixel TP, it is desirable forimprovement in transmittance that the bank layer BK and the organiclayer OL do not exist. Besides, for improvement in transmittance, a gateinsulating film of a thin film transistor connected to a lower electrodePX in another pixel may be removed in the transparent pixel TP.

Incidentally, in the pixel arrangement of the display area DP of therespective embodiments, the transparent pixel TP may be arranged insteadof the W pixel, or part of the W pixels may be replaced by thetransparent pixels TP. Specifically, all the W pixels in FIGS. 3 to 8and 10 to 12 may be replaced by the transparent pixels TP, or part ofthe W pixels may be replaced by the transparent pixels TP.

FIG. 15 shows an example of a sectional schematic view of a pixel areain an organic EL display device of an RGB separate coloring mode.

A color filter CF and a black matrix BM do not exist on an oppositesubstrate B2, and an organic layer OL1 is divided on a bank layer BK.(Material of the organic layer OL1 varies for each color pixel withrespect to a light-emitting layer, and is common to an electroninjection layer, an electron transport layer, a hole transport layer anda hole injection layer. In FIG. 15, the electron injection layer and thelike are omitted, and the organic layer OL1 is divided on the bank layerBK.) Further, a W pixel does not exist in the organic EL display deviceof this mode, but R pixels, G pixels and B pixels exist. Y pixels, Cypixels and Mg pixels may also exist.

The mode of FIG. 15 can be applied to display devices in which all the Wpixels in FIGS. 3 to 8 and 10 to 12 are replaced by the transparentpixels TP. Further, the mode can be applied to the right side of FIG.13. The transparent display can be formed in this way, and thetransmittance thereof is proportional to the area density of thetransparent pixel TP.

In this case, in order to increase the transmittance, the opening of thetransparent pixel TP is larger than that of at least the G pixel, and ispreferably equal to or larger than that of the B pixel and the R pixel.

Since the separately coloring system is adopted as in FIG. 15, lightquantity is not reduced by a color filter. Thus, low power consumptionprocessing by the W pixel is unnecessary in principle. Further, sincethe W pixel does not exist, the place of the W pixel can be replaced bya light translucent part, and the transmittance of the transparentdisplay can be increased. Image processing required by the insertion ofthe W pixel also becomes unnecessary. Thus, the development cost isreduced, power consumption increase due to the image processing does notoccur, and a circuit for the image processing and an program storagearea become unnecessary. The organic layer OL1 of the W pixel is notnaturally required to be formed. Incidentally, the electron injectionlayer, the electron transport layer, the hole transport layer and thehole injection layer may be separated by the bank layer BK in each colorin order to prevent electric color mixture. Alternatively, the electroninjection layer, the electron transport layer, the hole transport layerand the hole injection layer may be made common to the respectivepixels, and only the light-emitting layer in the organic layer OL1 maybe separated by the bank in the respective pixels. Besides, although theblack matrix is also removed, the black matrix may be provided on theopposite substrate B2 just above the bank layer BK in order to preventoptical color mixture. As a separately coloring method, a mask may beused to perform separately coloring, or a printing system such as inkjet may be used to perform separately coloring.

Incidentally, in FIG. 15, a black matrix does not exist. Thus, alight-emitting area ER corresponds to an opening of each pixel. Thelight-emitting area ER is an area where a lower electrode PX, an organiclayer OL1 and an upper electrode CD contact each other, and is an areawhere light is emitted when current flows through these components.

Besides, the transmittance from the back side to the front side of thetransparent display of the fifth embodiment is proportional to the areadensity of the transparent pixel TP in the display area DP. If the blackmatrix BM is formed on the opposite substrate B2, the opening area ofthe transparent pixel TP by the black matrix BM is preferably madelarger than the opening area of the high definition pixel (G pixel), andis further desirably made equal to or larger than the opening area ofthe low definition pixel (R pixel and B pixel). Besides, if the blackmatrix BM is not formed on the opposite substrate B2, the opening areaof the transparent pixel TP partitioned by a wiring such as a firstscanning line BG or a video signal line Data is preferably made largerthan the light-emitting area of the G pixel by the organic layer OL, andis further desirably made equal to or larger than the light-emittingarea of the R pixel and the B pixel by the organic layer OL.

Although the organic EL display device 1 of the fifth embodiment isdescribed in the above, the description is made mainly on the differentpoints from the organic EL display device 1 of the first embodiment, andthe description of almost the same point as that of the case of thefirst embodiment is suitably omitted.

FIG. 16 shows a relation between a unit area M as a main pixel and animage address. Hereinafter, sub-pixels arranged in the unit area M asthe main pixel in the respective embodiments will be described by usingFIG. 16.

P(x,y) represents an image address of an arbitrary place. As shown inFIG. 16, the image address is sequentially scanned from left to right atthe first row in one frame, and the organic EL display device 1 isdriven in accordance with the read display data. Next, the image addressis scanned from left to right at the second row, and scan issequentially performed at a lower raw, and finally, P(m,n) is scanned.The organic EL display device 1 is driven in accordance with the readdisplay data. Here, m, n, x and y are respectively natural numbers.

An area of the organic EL display device 1 corresponding to each P(x,y)is the unit area M. With respect to data stored at P(x,y) correspondingto the unit area M, the same pixel data is stored for each color, dataare different for different colors. For example, when two R pixels, twoB pixels, three R pixels and one W pixel are included in the unit areaM, the same data read from P(x,y) are used for the two R pixels in theunit pixel M, the same data read from P(x,y) are used for the two Bpixels, the same data read from P(x,y) are used for the three G pixels,and the same data read from P(x,y) are used for the one W pixel. Withrespect to each of the R pixel, the B pixel, the G pixel and the Wpixel, different data of storage areas corresponding to different P(x,y)are used.

Incidentally, although the display device of the respective embodimentsis the organic EL display device 1, the invention is not limited tothis. For example, the display device may be a self light-emittingdisplay device in which each pixel of the display area DP includes aself light-emitting element such as a quantum-dot light emitting diode(QLED), or a liquid crystal display device. Besides, the display devicemay be a bottom emission type self light-emitting display device.

While there have been described what are at present considered to becertain embodiments of the invention, it will be understood that variousmodifications may be made thereto, and it is intended that the appendedclaims cover all such modifications as fall within the true spirit andscope of the invention.

What is claimed is:
 1. A display device comprising: low definitionpixels as sub-pixels, each of the low definition pixels having an arealarger than a specified standard area; high definition pixels assub-pixels, each of the high definition pixels having an area smallerthan the specified standard area; and transparent pixels larger than thelow definition pixels, wherein the low definition pixels, the highdefinition pixels, and the transparent pixels are included in each ofunit areas which are regularly arranged, the low definition pixelsinclude blue pixels and red pixels, the high definition pixels includegreen pixels, each of the red, green, and blue pixels includes anorganic light emitting element and a transistor connected to the organiclight emitting element, none of the transparent pixels includes anyorganic light emitting element or any transistor, none of the red,green, and blue pixels overlaps with any of the transparent pixels, andnone of the transparent pixels is configured to be controlled by anyswitch element in each of the transparent pixels.
 2. The display deviceaccording to claim 1, further comprising: an element substrate on whichthe organic light emitting element and the transistor is formed; and anopposite substrate facing the element substrate, wherein the transparentpixels each are configured to transmit light coming into the elementsubstrate and going outside of the opposite substrate.
 3. A displaydevice comprising: a plurality of first pixels each of which includes ared pixel or a blue pixel and has a first area; a plurality of secondpixels each of which includes a green pixel and has a second area; and aplurality of third pixels each of which includes a transparent pixel andhas a third area, wherein the first area is larger than the second area,the third area is larger than the first area, each of the plurality offirst and second pixels includes an organic light emitting element and atransistor connected to the organic light emitting element, none of theplurality of third pixels includes any organic light emitting element orany transistor, none of the plurality of first and second pixelsoverlaps with any of the plurality of third pixels, the plurality offirst and second pixels are arranged in a matrix in plan view along twoorthogonal axes, the two orthogonal axes extending in a first direction,in a second direction perpendicular to the first direction, in a thirddirection opposite to the first direction, and in a fourth directionopposite to the second direction, each of the plurality of first pixelsis adjacent to respective ones of the plurality of third pixels in thefirst direction, the second direction, the third direction, and thefourth direction in plan view, and each of the plurality of secondpixels is adjacent to respective ones of the plurality of third pixelsin the first direction, the second direction, the third direction, andthe fourth direction in plan view.
 4. The display device according toclaim 3, further comprising: an element substrate on which the organiclight emitting element and the transistor is formed; and an oppositesubstrate facing the element substrate, wherein the transparent pixel isconfigured to transmit light coming into the element substrate and goingoutside of the opposite substrate.
 5. The display device according toclaim 3, wherein the plurality of second pixels are provided in morenumber than each of the red pixel and the blue pixel.
 6. The displaydevice according to claim 3, further comprising: an element substrate onwhich the organic light emitting element and the transistor is formed;and an opposite substrate facing the element substrate, wherein theelement substrate has a first side, a second side, a third side, and afourth side in plan view, the first side runs along a fifth direction,the second side runs along a sixth direction, the third side runs alonga seventh direction, the fourth side runs along an eighth direction, thesixth direction is perpendicular to the fifth direction, the seventhdirection is an opposite direction to the fifth direction, the eighthdirection is an opposite direction to the sixth direction, and each ofthe fifth and seventh directions is perpendicular to each of the sixthand eighth directions, and each of the fifth, sixth, seventh, and eighthdirections differs from each of first, second, third, and fourthdirections.
 7. The display device according to claim 3, wherein acentral portion of each of the plurality of first pixels is adjacent torespective ones of the plurality of third pixels in the first direction,the second direction, a third direction, and a fourth direction in planview, and a central portion of each of the plurality of second pixels isadjacent to respective ones of the plurality of third pixels in thefirst direction, the second direction, a third direction, and a fourthdirection in plan view.